Engine piston



Jan. 22, 1929. 1,699,621

H. J. NESS ENGINE PISTON Filed April 8, 1926 avwemtoz HIROLD J 583 33 Ma Qua/neg Patented Jan. 22, 1929.

UNITED STATES PATENT OFFICE.

HAROLD J. NESS, OF JERSEY CITY, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO THE CLEVELAND TRUST COMPANY,

OHIO.

OF CLEVELAND, OHIO, A CORPORATION OF ENGINE PISTON.

Application filed April 8,

Fig. 1 is an elevation, partly in section, of a completed piston embodying my invention; and Fig. 2 is a bottom plan thereof.

My invention relates to engine pistons, and

particularly to aluminum pistons of the split or slotted skirt type. The use of aluminum pistons in internal combustion engines is particularly desirable because of their lightness in weight and theirability to dissipate heat.

lhey are objectionable because of their large coeflicient of expansion, and to obviate this objection and lessen the clearance which would otherwise be required, the skirts of the pistons are slit so as to prevent seizing in the m cylinder when expanded from heat or too great looseness when contracted or cold. The objection to slit pistons is that it is extremely difficult to produce pistons of definite dimen-' sions because they must be machined before being slit and, when slit, because the slitting relieves strains which have been set up in the rectal of'the skirt, they are extremely apt to assume forms out of a true circle. Thereafter, because the slit in the skirt permits a as springing action between the portions of the skirt separated by the slit, accurate machining is extremely diflicult, if not impracticable. Further, under the hammering of actual use they have a tendency to distort out of shape as well as to collapse under either the compression or power stroke.

My invention obviates these difliculties, since the advantages of the lightness and close fit of the aluminum split skirt pistons are retained, but the disadvantages are eliminated. I accomplish this by forming the skirt of my improved piston so that when slit the slit portions of the walls support each other during machining or when in use, while at the same time seizing is revented ust as in the split skirt type. y invention also comprises various features which I shall hereinafter describe and claim.

Referring to the drawings, in which I have shown a piston of a type largelyused in automobile internal combustion engines, the head 2 has depending webs 3 which connect the head with the piston pin bosses 4. Substantially at right angles to the pin bosses 4 are the plates 5, which are curved from their points of juncture 6 with the skirt 7 to give a slightly resilient connection between the skirt 7 and plates 5. While the u per porm 7 of the skirt does not exten circum- 1926. Serial No. 100,496.

ferentially beyond the points of juncture wit-h the plates 5 in the region of the piston 'pin bosses 4, below the plates 5. the skirt is in the form of a substantially complete circle. This lower circular portion 7 of the skirt is preferably interrupted on the exterior by a vertically extending groove 8, here shown as extendin from the lower to the upper edge of the skirt in one of the portions 7 between the plates 5 and intersecting the space 9 which lies between the upper edge of the skirt 7 and the piston head 2.

The recess 8 is preferably substantially V- shaped, but with one leg extending so. that the wall 10 of the skirt at one side of the V extends more nearly normal to the periphery of the skirt than the wall 11 at the other side of the V. This is for the purpose of per mittmg a saw to out through the wall 10 at an angle as nearly parallel to a center line runmng through the wrist pin bosses 4 as possible to form a slot 12.

When the slot 12 has been cut through the wall 10, it will be seen that the cut ends of the skirt on either side the slot 12 are free to expand circumferentially, and that the walls 10 and 11 form aportion which is goosenecked in cross sectlon, and that the end 13 can not be pressed inwardly because supported by the gooseneck, while the goosenecked end can not s ring out because limited by the end 13. As t e skirt of the piston expands there is a slidin circumferential action between the slotted portions of the skirt, but radial movement of the one is resisted by the other. It will therefore be seen that it is desirable to have the slot 12 at a substantial angle to any radial plane through the vertical axis of the piston in order that one skirt portion should support the other and yet permit such sliding action.

The support afforded by the slotted ends of the skirt holds the skirt substantially in circular form, so that after being slotted the pistons may be machined to the exact measurement desired in the form of a true circle.

If desired, the slot 12 may be formed in'the piston during the casting operation, thus obviating the necessity of cutting the slot after the piston has been cast.

' 'When pistons of my improved design are in use they are found to have a much more accurate fit than types of split skirt pistons now commonly employed, as the mechanical bearing of one part of' the skirt on the, other supports the piston at the slot, prevents distortion and distributes the thrust of the power and compression strokes and results in giving a uniform bearing on the cylinder walls. By thus maintaining the piston in substantially true circular form, the oil is prevented from working up'along the skirt past the oil wiper ring of the piston head.

The terms and expressions whichl have employed are used asterms of description and not of limitation, and I have no intention, in the use of such terms and'expressions, of excluding any equivalents of the features shown and described, or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

W'hat I claim is:

1. An aluminum alloy piston having a head; a skirt; piston pin bosses connected to the head and the skirt, the skirt having a vertically extending line of division, the parts of the skirt on opposite sides of the dividing line having a bearing upon each other, said bearing forming a mutual support between the divided parts against collapse but permitting relative movement be- ,tween the two parts of the skirt separated by the said dividing line. I

2. An aluminum alloy piston havin a head; a skirt; piston pin bosses connected to the head and the skirt, the skirt having a vertically extending groove, and the wall of the groove having a slot therein, said slot completely disconnecting the adjacent parts of the wall; the said adjacent parts being on o posite sides of the slot and being capable of clrcumferential movement relative to each other but supporting each other against collapse.

3. An aluminum alloy piston having a head; a skirt; piston pin bosses connected to the head and the skirt, the skirt having a vertically extending groove; and the wall of the groove having a slot therein whereby theparts of the skirt on opposite sides of said slot are capable of circumferential movement relative to each other but support each other against collapse, the slot through the wall-of the skirt bein substantially tan ent to the inner circum erential surface of the skirt at one sideof the slot.

4. An aluminum alloy piston having a head; an annular skirt, piston pin bosses connected to the heal ;and the skirt, the skirt having a recess-which is of V-sliape in cross section, the wall of the skirt'at one side. of the V-shaped portion having a vertically extending slot therethrough to permit relative movement between the two-ends of the skirt on the opposite sides of the slot.

5. An aluminum alloy piston having a head; a circumferenti'ally extending skirt; piston in bosses connected to the head and skirt, t e skirt having an external vertically extending groove; a ortion of the wall of the groove retracted rom the circumference of the skirt having a slot therein whereby the parts of the skirt on opposite sides of said slot are capable of circumferential movement relative to each other but supporting each other against collapse.

6. An aluminum alloy piston having a head; a skirt; piston pin bosses connected to the head and the skirt, the skirt having a vertically extending slot through the wall thereof; the wall of the skirt at one side of the slot being retracted from the circumference described by the remainder of the wall of the skirt and terminating in a portion d1-v rected outwardly to the inner face of the wall on the opposite side of the slot whereby the parts of the slot are capable of circumferential move ment relative to each other but support each other against collapse.

HAROLD J. NESS.

skirt on opposite sides of said 

